arm64: dts: rockchip: set stdout-path on helios64

set the default output path to uart2

Signed-off-by: Dennis Gilmore <dgilmore@redhat.com>
Link: https://lore.kernel.org/r/20210715025635.70452-2-dgilmore@redhat.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>